Synthesis and Characterization of Lithium Nickel Manganese Cobalt Phosphorous Oxide

ABSTRACT

Disclosed herein are certain embodiments of a novel chemical synthesis route for lithium ion battery applications. Accordingly, various embodiments are focused on the synthesis of a new active material using NMC (Lithium Nickel Manganese Cobalt Oxide) as the precursor for a phosphate material having a layered crystal structure. Partial phosphate generation in the layer structured material stabilizes the material while maintaining the large capacity nature of the layer structured material.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of, and claims priority to, co-pendingU.S. Patent Application entitled “Synthesis and Characterization ofLithium Nickel Manganese Cobalt Phosphorous Oxide,” filed on Jun. 7,2016, and assigned application Ser. No. 15/175,298, which is adivisional of, and claims priority to, U.S. Patent Application entitled“Synthesis and Characterization of Lithium Nickel Manganese CobaltPhosphorous Oxide,” filed on May 8, 2013, assigned application Ser. No.13/889,514, issued on Jun. 12, 2016, and assigned U.S. Pat. No.9,388,045, both of which are incorporated herein by reference in theirentireties.

TECHNICAL FIELD

The present disclosure is generally concerned with processing techniquesfor materials synthesis for lithium ion batteries.

BACKGROUND

Conventional phosphate materials (e.g., LiFePO₄, LiMnPO₄) arestructurally stable materials that do not exhibit decomposition of thematerial when charged to high voltages (e.g., higher than 4.5V). Thestructure stability is also reflected by the fact that very small or noexothermic reactions are observed when heated to high temperatureswithout the presence of lithium residing in the structure. However, thephosphate materials do exhibit smaller theoretical capacity (around 170mAh/g) and lower electrical conductivity. As a result, conventionalphosphate material is restrictive or picky on the synthesis conditionsand electrode preparation methods for lithium ion battery applications.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the disclosure can be better understood with referenceto the following drawings. The components in the drawings are notnecessarily to scale, emphasis instead being placed upon clearlyillustrating the principles of certain embodiments of the presentdisclosure. Moreover, in the drawings, like reference numerals designatecorresponding parts throughout the several views.

FIG. 1(a) is an illustrative view of a crystal structure of aconventional structured LiNiO₂.

FIG. 1(b) is a diagram of an X-Ray Diffraction pattern for LiNiPO₂ inaccordance with embodiments of the present disclosure.

FIG. 1(c) is a diagram of an X-Ray Diffraction pattern for Li₃Ni₂PO₆ inaccordance with embodiments of the present disclosure.

FIG. 2 is a flow chart diagram depicting an exemplary synthesis processfor phosphate material in accordance with embodiments of the presentdisclosure.

FIGS. 3(a)-3(b) are diagrams illustrating results of an examination ofsynthesized materials using X-ray diffraction in accordance withembodiments of the present disclosure.

FIG. 4(a) is a diagram illustrating results of an examination ofsynthesized materials using X-ray diffraction in accordance withembodiments of the present disclosure.

FIGS. 4(b)-4(d) are diagrams illustrating results of an examination ofsynthesized materials and precursor materials using scanning electronmicroscope for comparison analysis.

FIG. 5 is a diagram showing phase evolution data for synthesizedmaterials during varying heat treatments in accordance with an exemplaryembodiment of the present disclosure.

FIGS. 6(a)-(c) are diagrams showing electrochemical properties ofexemplary electrodes in accordance with embodiments of the presentdisclosure.

FIG. 7 is a diagram of an exemplary embodiment of a furnace and a heattreatment environment for the synthesis of materials in accordance withthe present disclosure.

DETAILED DESCRIPTION

Disclosed herein are certain embodiments of a novel chemical synthesisroute for lithium ion battery applications. Accordingly, variousembodiments are focused on the synthesis of a new active material usingNMC (Lithium Nickel Manganese Cobalt Oxide) as the precursor for aphosphate material having a layered crystal structure. Partial phosphategeneration in the layer structured material stabilizes the materialwhile maintaining the large capacity nature of the layer structuredmaterial.

For comparison, conventional phosphate materials (e.g., LiFePO₄,LiMnPO₄) are structurally stable materials that do not exhibitdecomposition of the material when charged to high voltages (e.g.,higher than 4.5V). The structure stability is also reflected by the factthat very small or no exothermic reactions are observed when heated tohigh temperatures without the presence of lithium residing in thestructure. However, the phosphate materials do exhibit smallertheoretical capacity (around 170 mAh/g) and lower electricalconductivity. In contrast, the layer structured materials exhibit highertheoretical capacity (around 270 mAh/g) with better materials intrinsicelectrical conductivity.

In accordance with an embodiment of the present disclosure, a targetedphosphate material is Li₃Ni₂PO₆ (⅓ of the transition metal sites arereplaced by phosphorous) and its derivatives (less than ⅓ of transitionmetal sites are replaced by phosphorous). This material has a highertheoretical capacity of 305 mAh/g. Meanwhile, this new class of materialcan be modified to stabilize the layer structured material byincorporating a different amount of phosphate (or phosphorous oxide)that renders this new class of material as exhibiting high capacity andsafety dual characteristics. As an example, the crystal structure (only1 unit cell) of conventional layer structured LiNiO₂ is shown forillustration in FIG. 1(a). A total of 12 atom layers are repeated in theLi—O—Ni—O order. If ⅓rd of the Ni sites are replaced by the phosphorousatoms, the material will be Li₃Ni₂PO₆ as mentioned earlier. If ⅙th ofthe Ni sites are replaced by the phosphorous atoms, the material willbecome Li₃Ni_(2.5)P_(0.5)O₆ (i.e., Li₆Ni₅PO₁₂), and so on. Forsimplicity, a general formula may be given as LiNi_((1-x))P_(x)O₂ forthis new class of material. The phosphorous will range from 0.33 to0.01. The simulated XRD (X-Ray Diffraction) patterns for LiNiPO₂ andLi₃Ni₂PO₆ are shown in FIG. 1(b) and FIG. 1(c), respectively, forillustrating the iso-structural nature of the phosphorous replacedmaterial. Further, from the enclosed experimental results, it is alsoapparent to synthesize materials with general formula ofLi_(x)X_(2/3+y)P_(1/3−y)O₂, 0≤x≤1, 0.001≤y≤0.33, where X can be Ni or acombination of transition metal elements, such as Cobalt, Manganese,Nickel, etc.

For one embodiment, NMC material (Lithium Nickel Manganese Cobalt oxide,LiNi_(1/3)Mn_(1/3)Co_(1/3)O₂) is particularly chosen as the synthesisstarting material (i.e., precursor). A reason, among others, is to leachout Manganese in the solution state that could expedite the diffusion ofPhosphorous ions (or phosphate ions) to the original positioned residingMn ions. Furthermore, the leached Mn can be re-grown on the surface ofthe skeletal material (the material being leached) and ensure goodelectrical conductivity of the synthesized material.

FIG. 2 shows the general synthesis steps utilized in an exemplaryembodiment of the present disclosure. To begin, NMC is leached (210)using acids. Next, the addition of carbonaceous materials facilitates(220) the formation of nano materials (primary particles). Then,phosphorous is dissolved (230) into the host structure, and a properamount of lithium (Li) containing compound may be optionally added(240). To form (260) a resultant electrode, the resulting solution iscooled (250) for direct coating of the slurry on a substrate. Afterwhich, heat treatments and calendaring may be applied to form (265)final electrodes.

Alternatively, to form a resultant material (280), the resultingsolution may be dried (272) to form powder precursors, or direct heattreatment (to high temperatures) may be applied (274) to the resultingsolution to form powders. After which, slurry and coating processes maybe applied to form (285) electrodes. Alternatively, direct calendaringof the resultant material on treated substrates followed by proper heattreatments may be performed (288).

For clarity, exemplary synthesis routes are described using thefollowing examples, in accordance with embodiments of the presentdisclosure.

EXAMPLE 1 Characterization of the Occurrence of the Phosphorous ReplacedLayer Structured Material with General Formula ofLi_(x)Ni_(1/4)Mn_(1/4)Co_(1/4)P_((1/4−y))O₂

1. Initially, dissolve oxalic acid (22.5 g (0.25 mole)) in CMC(carboxymethyl cellulose 1 wt % solution) (40 g) at 80° C.

2. Add LiNi_(1/3)Mn_(1/3)Co_(1/3)O₂ (97 g (1 mole)) to the solution. Atthis time, purplish foam evolves implying the dissolution of Mn into thesolution. Keep the solution at 80° C. for two more hours until reactionis completed.

Remarks: Step 1 and 2 are used for leaching Mn fromLiNi_(1/3)Mn_(1/3)Co_(1/3)O₂. The acid used in step 1 is not limited tooxalic acid. Formic acid, acetic acid, hydrochloric acid, or nitric acidmay also be used. However, organic acids are preferred in certainembodiments.

3. Add proper amount of carbonaceous materials. In this case, sucrose(67.5 g) was added into the solution. React for 2 more hours.

Remarks: Step 3 is used in facilitating the formation of nanocrystalline materials. The carbonaceous material is not limited tosucrose. Methyl cellulose (MC), Methylcarboxylmethyl cellulose (CMC),Cellulose acetate, starch, or styrene butadiene rubber may be used inachieving the same goal.

4. Then, add titrate phosphoric acid (38.3 g (0.33 mole, 85% in H₃PO₄content)) to the solution slowly (in half an hour).

5. Cool down the solution. At this moment, the solution is good fordirect coating on Al foil or can be dried to form powders for later onreaction. That is, the solution can be used in making the electrodedirectly or can be used in making powder materials.

In the case of direct coating process, since manganese oxalate(transition metal source), phosphate ions (phosphorous source), andaluminum substrates (aluminum source) are all present, the coatedsolution can adhere to the substrate when heat treated to hightemperatures, as described in U.S. patent application Ser. No.13/865,962, entitled “Methods and System for Making an Electrode Freefrom a Polymer Binder,” which is incorporated herein by reference in itsentirety.

In the case of powder formation process, the methods in drying thesolution can be flexible. This is usually conducted at 150° C. forseveral hours. FIG. 3(a) and FIG. 3(b) show the XRD data for theas-prepared powder (dried at 150° C.) being heat treated at 250° C. and330° C. separately for 4 hours in air. From FIG. 3(a) it can be seenthat the resultant material consists of two layer structured materialswith different lattice parameters. With the sample being heat treated at330° C., the two (003) peaks merged into only one broadened peak as anew material. This new material can be described with the followingreactions:

LiNi_(1/3)Mn_(1/3)Co_(1/3)O₂+⅓H₃PO₄→4/3Li_(3/4)Ni_(1/4)Mn_(1/4)Co_(1/4)P_(1/4)O₂+balancedH and O,

with the creation of 25% Li vacancies or

LiNi_(1/3)Mn_(1/3)Co_(1/3)O₂+⅓H₃PO₄→Li₀Ni_(1/3)Mn_(1/3)Co_(1/3)O₂+⅓Li₃PO₄+balancedH and O,

with the creation of 100% Li vacancies.

Since trace Li₃PO₄ is observed in the resultant material, it may beconcluded that the resultant material is between the two extreme cases(i.e., partial phosphorous incorporated layer structured material) withresidual Li₃PO₄.

It should be mentioned that no olivine structured materials wereobserved from the XRD data. So, the occurrence of layer structured,partial replacement of transition metal sites with phosphorous ions canbe concluded as the structure of the resultant material. If amicroscopic view is implemented in this example, one can also concludethat the resultant material is comprised of layer structured materialswith different lattice parameters.

EXAMPLE 2 Characterization of the Occurrence of Nano CrystallineFormation During the Transformation of NMC toLi_(x)Ni_(1/4)Mn_(1/4)Co_(1/4)P_((1/4−y))O₂

1. Initially, dissolve oxalic acid (22.5 g (0.25 mole)) in CMC(carboxymethyl cellulose 1 wt % solution) (40 g) at 80° C.

2. Add LiNi_(1/3)Mn_(1/3)Co_(1/3)O₂ (97 g (1 mole)) to the solution. Atthis time, purplish foam evolves implying the dissolution of Mn into thesolution. Keep the solution at 80° C. for two more hours until reactionis completed.

Remarks: Step 1 and 2 are used for leaching Mn fromLiNi_(1/3)Mn_(1/3)Co_(1/3)O₂. The acid used in step 1 is not limited tooxalic acid. Formic acid, acetic acid, hydrochloric acid, or nitric acidmay also be used. However, organic acids are preferred in certainembodiments.

3. Add proper amount of carbonaceous materials. In this case, methylcellulose (MC) (67.5 g) was added into the solution. React for 1 hour.

4. Add 30 g of n-Butanol for 3 more hours of reaction.

Remarks: Step 3 and 4 are used in facilitating the formation of nanocrystalline materials. The carbonaceous material is not limited tosucrose. Methyl cellulose (MC), Methylcarboxylmethyl cellulose (CMC),Cellulose acetate, starch, or styrene butadiene rubber may be used inachieving the same goal.

5. Then, add titrate phosphoric acid (38.3 g (0.33 mole, 85% in H₃PO₄content)) to the solution slowly (in an hour).

Remarks: Steps 5 was utilized in dissolving phosphorous into thestructure. Then, the resultant slurry was transferred to a metallicaluminum boat and heat treated to 300° C. for 4 hours in air in a boxfurnace. The heat treated material's XRD data is shown in FIG. 4(a).Meanwhile, FIG. 4(b) and FIG. 4(c) are the SEM (scanning electronmicroscope) pictures representing the heat treated material (20 kX) andthe original NMC material (10 kX) (before any treatment) forcomparisons. It can be seen that the morphology of the heat treatedmaterials is nano particles (primary particle) in nature, which is verydifferent from the original NMC materials morphology.

FIG. 4(d) is an additional SEM picture conducted by cross sectioning theheat treated material. It can be seen that the heat treated material ispretty much porous in nature which can be reflected by the physical datashown in Table 1 as the surface area has been increased from 0.4 to 6m²/g.

TABLE 1 Surface Particle size Data (um) Area Data D10 D50 D100 (BET)(m²/g) LiNi_(1/3)Mn_(1/3)Co_(1/3)O₂ 6.06 11.84 38.88 0.3867 Heat Treated6.08 12.84 42.69 6.0663 Material† Physical properties of the precursorNMC (LiNi_(1/3)Mn_(1/3)Co_(1/3)O₂) and the Example 2 heat treatedmaterial (300° C. for 4 hours). †Heat treated material was obtainedafter heat treating the sample at 300° C. for 4 hours.

EXAMPLE 3 Synthesis and Characterization ofLi_(x)Ni_(1/4)Mn_(1/4)Co_(1/4)P_((1/4−y))O₂ with the Addition of LiContent

1. Initially, dissolve formic acid (47 g (1 mole)) in MC (Methylcellulose 1 wt % water solution) (40 g) at 80° C.

2. Add LiNi_(1/3)Mn_(1/3)Co_(1/3)O₂ (97 g) (1 mole) to the solution. Atthis time, purplish foam evolves implying the dissolution of Mn into thesolution. Keep the solution at 80° C. for two more hours until reactionis completed.

Remarks: Step 1 and 2 are used for leaching Mn fromLiNi_(1/3)Mn_(1/3)Co_(1/3)O₂. The acid used in step 1 is not limited toformic acid. Oxalic acid, acetic acid, hydrochloric acid, or nitric acidmay also be used. However, organic acids are preferred in certainembodiments.

3. Add proper amount of carbonaceous materials. In this case, methylcellulose (MC) (20 g) was added into the solution. React for 1 hour.

4. Add 30 g of n-Butanol for 1 more hour of reaction.

Remarks: Step 3 and 4 are used in facilitating the formation of nanocrystalline materials.

5. Then, add titrate phosphoric acid (28.8 g (0.25 mole, 85% in H₃PO₄content)) to the solution slowly (in an hour).

6. Prepare the solution containing lithium on the side by dissolvingLi₂CO₃ (18.5 g) in formic acid/water (ratio 30 g/60 g) solution. 18.5 gLi₂CO₃ is equivalent to 0.5 mole of Li content.

7. Add the solution prepared in step 6 to the solution resulted fromstep 5.

Remarks: Step 5 was utilized in dissolving phosphorous into thestructure and step 6 was used in increasing the lithium content (e.g.,decreasing Li vacancies in the structure as mentioned in Example 1).

8. Then, increase the solution temperature from 80° C. (kept from step 1to 6) to 110° C. for drying the solution. The dried xerogel was crushedinto powder form to be ready for the following heat treatments.

FIG. 5 shows the phase evolution data for the as-prepared powder and thesamples being heat treated at 300° C., 380° C., 450° C., 550° C., and650° C. separately for 4 hours in oxygen. Original NMC precursor is alsoplaced for comparisons. From FIG. 5, it can be seen that the heattreated materials showed broadened peaks implying the formation ofphosphorized material with new nano crystallines formed on the surfaceof the resultant materials. Before the heat treatments, the as-preparedpowder shows a mixture of manganese formate (hydrated and non-hydrated)and the leached NMC materials. So, it is apparent that the newly formednano crystalline materials can result from the formation of LiMn₂O₄, ornano (amorphous) LiMnPO₄ during the heat treatment processes. Otherimpurities such as Li₃PO₄ can be a consequence of excess or non-reactedlithium and phosphate ions.

From the data described in Examples 1, 2, and 3, several new findingsmay be mentioned. First, it can be concluded that during the processesdisclosed in the present disclosure, the NMC material can bephosphorized. Second, during the formation of the phosphorized layerstructured material, new nano crystallines can be formed on the surfaceof the precursor material with the presence of the porous structure ofthe final material. It is apparent that the porous structure is formedduring the leaching process, and the leached material can re-grow ontothe parent material in the form of nano crystalline materials. Thebroadening of the peaks can be comprehended as the result of theexistence of phosphorized layer structured material and the newly formednano materials. The newly formed nano materials are originated mainlyfrom the presence of leached manganese (formate). Next, heat treatmentsto elevated temperatures (please refer to the phase evolution studyshown in FIG. 5) does not change the peak broadening nature of thematerial implying the stability of the phosphorized phase can bemaintained with the increase of temperature.

Accordingly, from the aforementioned examples, occurrence of phosphatematerial was observed corresponding to the general formula:

Li_(x)Ni_(1/4)Mn_(1/4)Co_(1/4)P_((1/4−y))O₂, 0≤x≤1, 0.001≤y≤0.25.

The following examples may be used in characterizing the materialsdescribed above. Two exemplary methods used in making exemplaryelectrodes in accordance with the present disclosure are described.

Method 1 Conventional Method in Making the Slurry and Coating on theAluminum Substrate

Example electrode preparation: Active material (5 g), Super P® (1 g) andSBR (Styrene-Butadiene Rubber) (0.3 g) were used in the slurry making.After coating using doctor blade, the coated electrode was dried at 110°C. for 3 hours followed by punching of the electrode. After vacuumdrying again at 110° C. for overnight, the electrodes were transferredto the glove box for test cell assembly. The test cell wasthree-electrode design with Li as the reference electrode.

Method 2 Direct Formation of the Material on the Substrate

For example electrode preparation:

1. Load the active battery material on top of the as made substrate byspreading the active material powder through a 250 mesh sieve of acalendaring machine.

2. Pass the as made (active material loaded) electrode through thecalendaring machine again for compacting the electrode.

3. Send the as made electrode to the box furnace for various heattreatments.

4. Punch the heat treated electrode and vacuum dry the samples at 110°C. for overnight. The dried electrodes were then transferred to theglove box for test cell assembly.

For substrate preparation:

i. Prepare 5M Phosphoric acid/n-Butanol solution (dissolve 23 gphosphoric acid and add n-Butanol to 40 ml in volume).

ii. Soak a substrate (Al plate) in the prepared solution that was keptat 50° C. for 2 minutes. Then, transfer the substrate to 100 mln-Butanol for rinsing. After rinsing, keep the substrate upright and dryat 50° C.

iii. Allow MnO₂ powders to pass through a 250 mesh sieve and spread onthe substrate. Then, take the loaded substrate for calendaring followedby a gentle heat treatment at 330° C. for 2 hours in air.

EXAMPLE 4

Electrochemical characterizations for the electrodes were made using theas-prepared powders described in Example 3, followed by heat treatingthe electrode at 330° C. for 4 hours in air. The electrode was madeusing the method 2 described above in which an average of 5.3 mg ofactive material was loaded on the substrate.

For the exemplary electrode, a charge capacity of 251 mAh/g wasobserved. The first discharge capacity was calculated to be 334 mAh/gwith two plateaus observed (please refer to FIG. 6(a)). The extremelyhigh first discharge capacity could be attributed to the new nanocrystalline material (oxides) formed on the surface of the skeletalmaterial.

EXAMPLE 5

Electrochemical characterizations for the electrodes were made using theas-prepared powders described in Example 3, followed by heat treatingthe electrode at 700° C. for 4 hours in oxygen. The electrode was madeusing the method 2 described above.

For the exemplary electrode, it was observed that the aluminum substratewas able to sustain a heat treatment of 700° C. under oxygen atmosphere.It should be noted that if the aluminum substrate is coated with activematerial on two sides, the aluminum substrate will be even stronger dueto the strong oxidizing environment. In this case, an electrode with 2.1mg loading of active material was tested.

A charge capacity of 231.7 mAh/g was observed. The first dischargecapacity was calculated to be 114.7 mAh/g with no obvious plateausobserved (please refer to FIG. 6(b)). The loss of charge capacity couldbe a result from the presence of the impurity phase observed shown inthe phase evolution study.

EXAMPLE 6

Electrochemical characterizations for the material synthesized using theas-prepared powders described in Example 3 were made by heat treatingthe as-prepared powders to 700° C. for 4 hours in oxygen. The electrodewas made using the conventional slurry making and coating method asdescribed in method 1.

In this example, an electrode with 2.8 mg loading (using the recipedescribed in method 1, active material is 81%) was tested. A chargecapacity of 108.5 mAh/g was observed. The first discharge capacity wascalculated to be 52.6 mAh/g with no obvious plateaus observed (pleaserefer to FIG. 6(c)). The shortage in capacity can be attributed to toosmall sample size used for the test. A corresponding c-rate of about c/3was used for testing the sample.

Any process descriptions should be understood as representing steps inan exemplary process, and alternate implementations are included withinthe scope of the disclosure in which steps may be executed out of orderfrom that shown or discussed, including substantially concurrently or inreverse order, depending on the functionality involved, as would beunderstood by those reasonably skilled in the art of the presentdisclosure.

FIG. 7 shows the design of a furnace and a heat treatment environmentfor the synthesis of the materials presently disclosed. FIG. 7 showsreaction vessel 1, which is open to air in furnace 2. The furnace isopen to the atmosphere at 3 a and 3 b so as to maintain substantiallyatmospheric pressure in the furnace. Flow of gases into or out of thefurnace is dependent on heating and cooling cycles of the furnace andchemical reactions taking place with materials in the furnace. Air isfree to enter the furnace, and air and/or products of a chemicalreaction of materials 4 in the reaction vessel 1 are free to exit thefurnace. Materials 4 in vessel 1 react chemically during heating stepsto form cathode materials in accordance with the present disclosure.Materials 4 in vessel 1, which face air found in the furnace, arecovered by a layer of a high temperature inert blanket 5, which isporous to air and escaping gases caused by the heating step. Heatingcoils of the furnace are indicated at 6.

It should be emphasized that the above-described embodiments are merelypossible examples of implementations, merely set forth for a clearunderstanding of the principles of the disclosure. Many variations andmodifications may be made to the above-described embodiment(s) withoutdeparting substantially from the spirit and principles of thedisclosure. All such modifications and variations are intended to beincluded herein within the scope of this disclosure and protected by thefollowing claims.

At least the following is claimed:
 1. A positive electrode material fora lithium secondary battery comprising a lithium nickel manganese cobaltphosphorous oxide material having a composition represented by:Li_(x)Ni_(1/4)Mn_(1/4)Co_(1/4)P_((1/4−y))O₂, wherein 0≤x≤1,0.001≤y≤0.25, wherein the positive electrode material further comprisesphosphorized material with nano crystallines formed on a surface of thelithium nickel manganese cobalt phosphorous oxide material, wherein thenano crystallines comprise nano (amorphous) LiMnPO₄ formed during a heattreatment process of the lithium nickel manganese cobalt phosphorousoxide material.
 2. A positive electrode material for a lithium secondarybattery comprising a lithium nickel manganese cobalt phosphorous oxidematerial having a composition represented by:Li_(x)Ni_(1/4)Mn_(1/4)Co_(1/4)P_((1/4−y))O₂, wherein 0≤x≤1,0.001≤y≤0.25, wherein the positive electrode material further comprisesphosphorized material with nano crystallines formed on a surface of thelithium nickel manganese cobalt phosphorous oxide material, wherein thenano crystallines comprise Li₃PO₄ formed from excess or non-reactedlithium and phosphate ions.
 3. A lithium metal phosphorous oxidematerial having a composition represented by:Li_(x)X_(2/3+y)P_(1/3−y)O₂, wherein 0≤x≤1, 0.001≤y≤0.33, and X is Nickelor a combination of transition metal elements.
 4. The lithium metalphosphorous oxide material according to claim 3, wherein X is acombination of Nickel, Cobalt, and Manganese elements.
 5. The lithiumnickel manganese cobalt phosphorous oxide material according to claim 4,wherein the material is comprised of layer structured materials withdifferent lattice parameters.
 6. A positive electrode material for alithium secondary battery comprising the lithium nickel manganese cobaltphosphorous oxide material according to claim 3.